Silicon surface chemistry is crucial to allow access to technologically interesting thin films not only
for electronic industries but also for biological applications. Silicon wafers were etched electrochemically using
ethanolic HF solution under different current densities (143 to 714 mA.cm-2) while etching time was adjusted
to obtain a constant charge of 4.5 C.cm-2 to generate pores of different sizes (50 to 1500 nm). Atomic Force
Microscopy (AFM) and Scanning Electron Microscopy (SEM) studies revealed the properties of porous layer
such as pore distribution, diameter, geometric shape of the pores, which depend upon HF concentration, current
density during electrochemical etching, temperature etc. Stability of the porous silicon wafer was achieved by
thermal oxidation. In this study, attempted were made to determine whether porous silicon can be used to bind
protein reversibly. Admittance and visualization of the protein (i.e. Bovine serum albumin) adsorption in pH
gated admission experiments were determined by atomic force microscopy. It was observed that the 66 kDa
BSA protein (~15 nm diameter) when positively charged (i.e. with citrate buffer, pH 4) would evenly coat the
negatively charged surface of an oxidized porous silicon. The bound protein could be eluted under conditions
that imparted a net negative charge on bound BSA (i.e., with phosphate buffered saline, pH 7). Thus, the
electrochemically machined porous silicon can be used as molecular sieve to trap protein molecule, which could
allow the in vitro study of protein-protein interactions.